Motor control system



y 1940- s. H. SWARTHOUT 2.199.600

nowoiz con'moL SYSTEI Filed June 12, 1939 I INVE VTOR Patented May 7, 194) Q g I I I UNITED STATES PATENT OFFICE MOTOR CONTROL SYSTEM Stanley H. Swartliout, Rochester, N. Y., assignol' to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application June 12, 1939, Serial bio/278,706 r 2 Claims. (01. 111-222) This invention relates to a governor for a uni- 53. Ring 53 is connected by wire 54 with half segversal motor whichwill operate either on direct ment 3|. Half segment 3| is connected by wire or alternating current. 55 with terminal bracket 62 of a speed responsive Y The type of universal motor speed control sysswitch 60.

i tem to which the present invention relates is the The centrifugal switch 60 comprises a disc 8| type shown in my copending application Serial drivenby the motor shaft 28. Disc 3| supports No. 215,426 filed June 23, 1938, now Patent No. the terminal bracket 62 and a terminal bracket 63 2,157,640, issued May 9, 1939. My application to which wire 56 is connected. Bracket 62 cardiscloses a system which includes two speed re-- ries a metal leaf spring member 64 the free end 0 sponsiv'e circuit breakers one of which is used of which carries a laminated weight piece 65 9 when the motor operates on direct current and carrying a contact 66 normally engageable with the other of which is used when the motor opera contact 61 carried by bar 68 riveted to a leaf ates on alternating current. It is the aim and spring 69 attached to the bracket 63. The norobject of my invention to provide a system of mal pressure of engagement between the concontrol in which one speed responsive circuit tacts 66 and 61 is regulated by an adjusting screw breaker is used to control the speed of the motor 10 threaded into a bracket 1| carried by the disc when operating either on direct or on alternating 8|. If the screw 10 is rotated so that it moves current, V 1 downwardly, as viewed in the drawing, the two Further objects and advantages of the present contacts 61 and 66 are moved downwardly tono invention will be apparent from the following degether thereby increasing the tension of the scription, reference being had to the accompanypr n S adjustment wo d ov rn he ing drawing wherein a preferred embodiment of motor for higher speed because greater centrifthe present invention is clearly shown. 118811 force would be qu to "Separate the I th drawing: contact 66 from the contact 61. Conversely, the

as The figure of the drawing is a wiring diagram motor can be r u a d or l wer speed by ,5 showing a motor control system embodying my threading the screw I0 upwardly, as viewed in the invention, v drawing, so as to reduce the tension between the In the drawing, designates a commutator contacts y r du in he tension of th sp i type series wound motor which operates either 6 whi h f c urse is bi ed upwardly as. viewe a on direct or alternating current. The motor t e drawing. The centrifugal switch 60 con- 90 brush 2| is connected with the field 22 which is cls the speed of the moto by ope s circonnected with line wire 23. The other brush cuit- As e speed of he mo or rises ab ve a 24 is connected by wires 25 and 29 with a colpredetermined value the contacts 66 and 61 seplector brush 30 engageable with a collector half Hate to decrease the Speed Of the O r- A segment 3|. The other half segment 32 is enthe speed falls below a predetermined value the 85 aged by a brush 33' carried by armature 34 of contacts close. relay 31 normally resting against the stop 35, as There is fairly rapid rate of Separation and shown in full lines, but movable by the attractive l sin f th conta ts 66 and 61 in ord r t vforce produced by magnet coil 36 into the dot m he speed of the motor. There will be some dash line position 34a in which its brush located a in at t s a s In order to produce as do at 33a engages a collector ring so. The pivot f at a nta t p ration as p ss th p la an of, arm 34 is connected with line wire 43. One of th dire t urr t pass n hr u th nend of magnet coil 36 is connected thro gh ontacts B8 and 61 is reversed twice for each revodenser 39 with wire 43 and th other e d of the lution of the shaft 28. Reversal of current is coil as is connected with a wire 40 connected also effected by the combination of e brushes 30 a with a relay 50 having a magnet coil- 4| which is d 33 w th the u ted C lle or f e8- connected by condenser 42 with wire 43. The col-- ments'3l and 32. lector brush an is connected by'wire u with con- In order t m n t effect of spark as denser 45 shunted by non-inductive resistance 46 ach of the s m nts 3 and 3 l v on rus w and connected with line wire 43. The relay so and go t c ta t w t a t r us each so has an armature 41 carrying a contact 43 normalseg e is P v at its e w inserts 1y out of engagement with a contact 49 which is of arc resisting metal such as tungsten. connected with wire 25 with collector brush 26. The disc BI is provided with a weight 15 to The armature 41 is connected by wire 5| with a counterbalance the centrifugal switch parts.

collector brush 52 engageable with collector ring For direct current operation, the magnets 38 u and 4| are deenergized so that contacts 43 and 49 of relay are opened and brush 33 on armature 34 of relay 31 is in the lower full line position. The circuit through the motor 20 includes line wire 23, field coil 22, brush 2|, armature 20a, brush 24, wire 25, wire 29, brush 30, collector segment 3|. wire 55, terminal bracket 62, contact arm 64, contact weight plate 65, contact 66, contact 61, contact plate 63, contact arm 69, terminal bracket 63, wire 56, collector segment 32, brush 33, arm 34, pivot 38, line wire 43. As previously explained, the brushes 30 and 33 cooperate with the half segments 3| and 32 to reverse the current across the switch contacts 66 and 61 twice during each revolution of the shaft 28.

When the motor is operating on alternating current the A. C. current will pass the condensers 39 and 42 and the relay magnet windings 36 and 4| of'relays 31 and 50, respectively, will be energized so that the contacts 43 and 43 will be closed and the arm 34 will be moved to the dot dash line position 34a thereby locating brush 33 at position 33a in contact with collector ring 58. Then the A. C. circuit of the motor is as follows: wire 23. field coil 22, brush 2|, armature 20a, brush 24, wire 25, contact 49 of relay 50, contact 43. armature 41, wire 5|, brush 52, ring 53, wire 54, wire 55, terminal bracket 62, arm 64, weight 65, contact 66, contact 61, plate 63, am 59, bracket 63, wire 56, wire 51, ring 58, brush 33 (at 33a), armature 34 (at 34a) pivot 33, lead 43.

The collector segments 3| and 32 are notin the A. C. circuit of the motor since current reversal at the contacts of switch is provided for by the alternating current.

The condenser 45 and the non-inductive resistance tend to reduce sparking at the contacts of relay 50.

From the foregoing description of the construction and mode of operation of my system, it is apparent that I have provided for the governing of the speed of a universal motor by means of circuit controlling relays and a single centrifugal switch, the contacts of which are protected during direct current, operation by a polarity reversing device driven by the motor.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

what is claimed is as follows:

1. A system of speed control for universal motors comprising, in combination, a universal motor adapted to operate either on direct or on alternating current, a centrifugal switch driven by the motor, a circuit making device driven by the motor and comprising a ring divided into two segments connected respectively with the terminals or the centrifugal switch and uninterrupted collector rings connected respectively with the terminals of said centrifugal switch, means including opposed brushes for normally connecting the divided ring in the circuit of the supply line and motor whereby the polarity of the centrifugal switch is reversed by the motor when operating on direct current, and means responsive to the passage of alternating current for connecting the collector rings-into the circuit of the supply line and motor and for disconnecting the divided ring.

2. The system according to claim 1 in which an A. C. relay connects one of the collector rings into the circuit of the supply line and motor and in which a second A. C. relay shifts a brush from the divided ring into contact with another of the collector rings.

STANLEY H. SWARTHOUT. 

